When AC2AA first came out, I played it, but I was using human plus and still didn't bother getting past the lost field. I had long ago sold my copies of AC2 and AC2AA, but I got nostalgic and re-bought AC2AA (but not AC2), and played through the whole thing legit for the first time. I was really fearing the confrontation with Nineball Seraph (AKA Ultimate Nineball), considering everyone always says he's the hardest opponent in the whole Armored Core series. Imagine my surprise when I beat him on like my third or fourth attempt. I was pretty close to beating him on my earlier attempts as well, but I made some dumb mistakes and he bladed me to death.
Seriously though, he's fast, but most of his weapons are pretty mediocre. His blades can do serious damage, but he tends to pause for a second right before he uses them, so it's not impossible to just dodge out of the way when you see a strike coming. How did this guy get the reputation he has?